Punch



W. PARKER Feb. 26, 1952 PUNCH Filed June 7, 1949 IN V EN TOR. W2 [/m We! Mv *Mu Patented Feb. 26, 1952 TED ENT. OFF 1 C 2,587,516; PUNCH willla n ParkenEast Cleveland, Ohio Application'Jnne 7, 1949, Serial N o. 917,5 6?

1 Claim. 7 (01. 33-191) This invention relates. to. improvements in. a.

punch and has for its primary object-to. provide a. punch which is particularly adapted to. be used in layout work by toolmakers, machinists, layout. men and the like where a. highv standard of accuracy is required.

An object of the invention is to provide apunch that is strongly-built, free from mechanical deficiencies, and isprovided, with means for quick, accurate and sure marking of a hole to be drilled.

In laying out a hole or holes to be drilled in tools, jigs, fixtures, machine parts, plates, machine parts for automobiles, airplanes, and other mechanical devices, it is customary, first to preparethe surface, then locatethe center of the hole to be drilled, then fix the center with a fine punch. A circle is then drawn with a very fine divider or compass, the exact. size of the hole. In the circumference-of the circle there arethen placed several punch marks to act as, guides in the drilling operation.

The above procedure requires time to place the centerpunch marks in the circle, and in doing so sometimes errors occur, because the circle may be under or over the exact size required,

with the result that the work must be gone over again, which results in the loss of time, besides the eye strain imposed upon the layout man in making the check.

Of course, it is to be understood that the drill is properly ground because full 95 per cent of the difiiculties encountered in drilling arise from faulty grinding of either of the point or the lip clearance of the drill.

An embodiment of the invention by way of example is illustrated in the annexed drawing, in which like reference numerals designate like parts throughout the same.

Figure 1 is a view partly in elevation and partly in section of a punch embodying the invention.

Figure 2 is a view in elevation of a punch and illustrating the collet like holder, adapted to removably mount the punch therein.

Figure 3 is a bottom of the punch looking in the direction of the arrows 2--2 in Figure 2.

Figure 4 is a view in elevation of the punch member removed from the holder.

In Figure 5 there is a diagrammatically shown. by way of example, how the sectors produced by the punch read with the circle now employed in the layout. The sectors produced by the punch are indicated by the arrows facing one another.

Figure 6 is a plan view illustrating the sectors formed by the punch, illustrated in Figure 2.

Figure 7 is a plan view showing the inscribed 2; circle and the center punchmarks therein, as now-generallyused by layoutmen.

Referring more particularly to the drawing by characters of reference, reference numeral 1 designates a holder or handle provided with collet like means for removably mounting a punch therein.

In thehandle or holder there are provided.

three concentric longitudinally extending bores, an upper bore 2, a middle bore 3 and a lower bore l. The wall 5 of the lower bore is provided with a plurality of elongated through slots 6, l, 8 and 9 radially extending and circumferentially spaced therein, adapted to provide a collet like hold on the removably mounted punch when mounted in the holder.

The punch I0 is provided with a cylindrical portion Ii, adapted to be removably held in the lower bore 4. by thev collet like structure of the holder. The punch is provided with a smooth longitudinally extending through bore 12 adapted to receive a centering means hereinafter described. The punch is provided with a head portion l3 machined to a predetermined diameter as at 14 in the respective figures of the drawing, to produce a marking edge l5. The edge is produced by machining the head portion to a predetermined obtuse or acute angular configuration.

The surface of the punch is interrupted by milling a plurality of grooves across its face as shown at I6 in Figure 3, to produce a plurality of segments I l as shown in Figure 3. The sectors which are limited by the arrowed lines illustrated in Figure 5 are a replica of the marking edge l5 on the segmental section of the punch, a bottom view of which is illustrated in Figure 3. In instance where the hole to be laid out is of very small diameter, the marking edge of the punch may be left intact because of the dimculty of milling grooves to interrupt it.

In Figure 6, the sectors I8, l9, 2i] and 2!, illustrates the sectors produced by the punch illustrated in Figure 2.

In Figure 7 the system now used is illustrated. It is obvious that a toolmaker, machinist or layout man will appreciate the fact when Figures 6 and 7 are carefully studied, that the punch has a great time-saving advantage and that'the precision of the machined marking edge produces more easily, surely and rapidly, accurate marking for a drilling operation than the present system now used.

In the holder there is provided a centering means 22 scientifically hardened and ground. Its

conical end 23 is precision ground so that it is adequate for maintaining the high standard of accuracy in vogue today in the layout field. The centering means is slidably and rotatably mounted in the bore in the punch, so that wear in the bore in the punch is retarded and its movement therein is firm and steady.

The upper end portion 24 of the centering means is reduced to form a shoulder 25 on which the lower end 26 of the helical spring 21, of the expansible type may bear, and normally holds the centering element in the position shown in Figures 1 and 2. In the centering element there is provided a transverse pin 28 that prevents it p from being forced out of the holder byengaging the top end 29 of the punch.

The flange 30 which tightly cooperates with a portion of the periphery of the wall'of the handle,

serves to prevent the portions from being dissymmetrically forced outwardly in a radial direction when the punch is mountedin the collet like portion of the handle. The flange also serves to position the fingers on the punch while in use to give ease in handling,

The operation of the punch is as follows:

After the center has been located for the hole to be drilled, the pointed end of the centering element is placed in the punch mark made to indicate its center, the holder is then pushed down on the centering element until the marking edges are brought into contact with the surface of the material to be drilled, the marking edge being machined assures a firm contact therewith so that it will not tilt or topple over, the holder is then struck with a hammer on its top end, with the result that the sectors are indented on the surface to indicate the proper position of the hole to be drilled.

I am aware that my invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof; and I therefore desire that the present embodiment be considered in all respects as illustrative and not 4 restrictive, reference being had to the appended claim rather than to the foregoing description to indicate the scope of the invention.

Having thus described my invention, what I claim is:

A tool of the class described, comprising, in combination, a holder having three bores therein concentrically positioned with the axis thereof consisting of an upper bore, a middle bore and 3; lower bore, the Wall of the lower bore being provided with diametrically aligned slots adapted to provide a collet like structure, a removably mounted punch mounted in the collet like structure, a centering element slidably mounted in the punch and provided with a reduced upper portion to provide a shoulder, and being transversely apertured adjacent said shoulder to permit insertion of a pin therethrough, the pin adapted to prevent the centering element from being forced out of the punch, an expansible spring mounted on and surrounding the reduced upper portion of the centering means and in the upper bore, the pin adapted to slide friction free in the middle bore, a flange mounted externally on the punch and cooperating with the collet portions formed by the diametrically aligned slots to prevent the punch from forcing the collet portions dissymmetrically when the punch is mounted in the collet like portion of the holder.

WILLIAM PARKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

